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We have such a mechanism, in progress at least: The SIP configuration
framework (see http://tools.ietf.org/html/draft-ietf-sipping-config-
framework-11). It supports SIP-based event notifications for
configuration updates. As I said in an earlier message, re-inventing
a subset of the configuration framework just for this purpose seems
counterproductive.
On Apr 16, 2007, at 1:35 PM, Brian Rosen wrote:
Okay, let's look at this.
For fixed devices, the PSAP URI doesn't change often, the cached
value is
very likely to be good. However, it MIGHT change on short notice.
The call
time query fixes this, if it works.
For mobile devices, the endpoint may get a reference. The
REFERENCE doesn't
change. It's good for a long time (probably as long as the carrier -
subscriber relationship holds). If it gets a value, then it wants
an update
when it moves beyond the PSAP boundary. With a value, it queries
LoST and
gets the boundary, then passes that to its location determination
mechanism
and asks for a notification when it moves beyond that.
The above, of course, is fairly far from what IMS currently talks
about, but
that is what the IETF ecrit/presence architecture would say.
If the access network plays cozy with the location, so it passes a
reference
and a PSAP URI, then it needs a way to TELL the device when the
PSAP URI is
no longer valid. Perhaps we could define a SIP event package for this
purpose, so a LIS could notify an endpoint of a new PSAP URI when its
current location warranted that. I suppose this is a presence
thing, and
maybe we could tie this more strongly into the existing presence
system.
Brian
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